Changes
Nova
,/* Ports */
In the fourth page, the last 8 bytes are not normal RAM, but can be used to read and write the time from the realtime clock.
Assuming the interface is mapped at 6000-7FFF:
{| class="wikitable" style="text-align:center;"
|-
! rowspan="2" | Address
! colspan="8" | Data
! rowspan="2" | Function
! rowspan="2" | Range (BCD)
|-
! D7 !! D6 !! D5 !! D4 !! D3 !! D2 !! D1 !! D0
|-
| 7FFFh || colspan="4" | 10 Years || colspan="4" | Year || Year || 00-99
|-
| 7FFEh || 0 || 0 || 0 || 10 M. || colspan="4" | Month || Month || 01-12
|-
| 7FFDh || 0 || 0 || colspan="2" | 10 date || colspan="4" | Date || Date || 01-31
|-
| 7FFCh || 0 || FT || CEB || CB || 0 || colspan="3" | Day || Century/<br />day || 00-01/01-07
|-
| 7FFBh || 0 || 0 || colspan="2" | 10 hours || colspan="4" | Hours || Hours || 00-23
|-
| 7FFAh || 0 || colspan="3" | 10 minutes || colspan="4" | Minutes || Minutes || 00-59
|-
| 7FF9h || ST || colspan="3" | 10 seconds || colspan="4" | Seconds || Seconds || 00-59
|-
| 7FF8h || W || R || S || colspan="5" | Calibration || Control ||
|}
Legend:
*S = SIGN bit
*R = READ bit
*W = WRITE bit
*ST = STOP bit ('1' stops the oscillator)
*CB = CENTURY bit
*CEB = CENTURY ENABLE bit (when CEB is set to '1,' CB will toggle from '0' to '1' or from '1' to '0' at the turn of the century)
*FT = FREQUENCY TEST bit (must be set to '0' upon power for normal operation)
*0 = Must be set to '0'
*Calibration (The oscillation rate of any crystal changes with temperature. The accuracy is greatly improved by properly setting the calibration bits)
== Software ==
